Indoor-locating systems, in general, use sensors to locate the real-time position of a device, within a building. The devices may be asset tags, personnel badges, or portable devices. Those skilled in the art will recognize that portable device means a portable computing device such as a mobile telephone, smartphone, tablet or laptop computer. Some indoor-locating systems are indoor-wayfinding systems. Indoor-wayfinding systems that run as applications on portable devices provide guidance to people who are moving around within a building. Much as the Global Positioning System (GPS) provides location information to portable devices which are outdoors, and much like mapping systems provide suggested routes for navigating to a destination outdoors, an indoor-wayfinding system can provide location and route information within a building.
GPS satellites can provide a position estimate outdoors, but GPS satellites are not typically strong enough to provide a position estimate indoors. Therefore, owners of public buildings have been deploying “beacon” networks indoors, to provide location reference points. These “beaconing” location-reference points typically send out a radio message to portable devices such as mobile phones. The phones, when running an application, listen for the radio beacons, and run an algorithm to estimate their location in the building. The application can then use the location information and its mapping logic to suggest routes to destinations within the building.
One typical site for use of the indoor-wayfinding beacons and mobile-phone applications is hospitals. Patients and families of patients enter a hospital with a specific destination in mind. They may carry a portable device such as a mobile phone. The hospital wants to help patients to find caregivers, departments, and resources within the hospital, to improve their patient experience, and to assure that patients can arrive at their appointments on schedule. The hospital wants to help patients' family members navigate to find their loved ones. Hospitals may be well-signed with navigation signs, but the patients and family members may prefer the help of a phone-based wayfinding application which can show them a constant blue-dot on a map to verify their current location in the hospital, and they may prefer the help of a wayfinding application to provide them turn-by-turn directions.
Patient wayfinding systems in hospitals are mature. But typically the wayfinding system in a hospital provides a location estimate, not a precise room-level read. The location estimate is frequently based strictly on radio signals, which suffer from transmission impairments (blockage, reflection, absorption, interference) and travel through walls, so the mobile phone cannot determine from just the radio signals alone, which room it has entered.
This lack of room-level specificity means that traditional wayfinding systems are not accurate enough, in their location reports, to support use cases that require room-level accuracy. For example, some use cases need to know with 100% certainty that a doctor has entered room 601 rather than room 602. Assume the doctor is carrying a phone, and the phone has a locating or wayfinding application. The locating and wayfinding system that uses just radio signal strength will struggle to report which room the doctor has entered with the desired accuracy.
Use of a second technology is required to determine with near 100% accuracy which room the doctor's phone has entered. The current invention proposes the use of a room-level motion sensor in each patient room of the hospital. One room-level motion sensor in room 601 can sense whether a person has just entered room 601. A second room-level motion sensor in room 602 can sense whether a person has entered room 602. The phone and wayfinding app may be somewhat confused about which room it has entered based solely on radio signals, but the motion-sensing beacons' information will supplement any radio signal-strength indication (RSSI). Fusing together motion and RSSI information will give a better location estimate than RSSI can provide by itself.
Another potential solution to the 100% room-level-accuracy challenge are Real Time Location Systems (RTLS). Some RTLS systems can provide room-level accuracy to some devices in rooms, but most RTLS systems struggle to provide room-level accuracy to phones without adding an exterior tag to the phone.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.